Investigation into the alterations in protein composition of the lens were conducted with particular reference to membrane proteins. Development and refinement of in vitro model systems for cataract development have continued. Results from these in vitro systems indicate many of the steps during cataract development proceed in a very similar manner regardless of the initiating event in cataractogenesis. Gylceraldehyde phosphate dehydrogenase, an enzyme in the glycolytic pathway, has been studied in vivo and in vitro. The possible inactivation of the enzyme during cataract formation has been under investigation. Cultures of lens epithelial cells as well as other cells from tissue culture have been utilized to study basement membrane formation, cytotoxic agents, and enzymes such as aldose reductase. These cells are beneficial because they facilitate the study of biological events in a well-defined and easily manipulated system.